检索结果-内蒙古大学图书馆

New method for developing optical code division multiplexed access sequences using genetic algorithm

optical ENGINEERING 1999年第1期38卷 151-156页

作者： Sadot, D Mahlab, U Bar Natan, V Ben Gurion Univ Negev IL-84105 Beer Sheva Israel Ctr Technol Educ IL-58102 Holon Israel

A new method for developing optical code division multiplexed access (CDMA) address code sequences is presented. The method is based on the genetic algorithm, which has already shown success in developing two-dimensional correlation functions for pattern recognition. The algorithm is very flexible in its optimization criteria and is thus adequate for various optical CDMA applications, including coherent and noncoherent systems. Preliminary computer experimental results are presented that indicate very good discrimination ratios and very fast convergence of the search process. important implications include synchronization-independent CDMA system design, reduction in optical beat noise, optical power budget improvement, and enhanced security. (C) 1999 Society of Photo-optical Instrumentation Engineers. [S0091-3286(99)01901-7].

关键词： optical CDMA genetic algorithm optical communication optical coding

来源：评论

学校读者我要写书评

暂无评论

Geometric Super-resolution using Negative Rect Mask

引用

OPTIK 2018年 168卷 323-341页

作者： ul Haq, Ihtsham Mudassar, Asloob A. PIEAS DPAM Islamabad Pakistan Pakistan Council Sci & Ind Res NPSL Islamabad Pakistan

In an electronic imaging system, image is retrieved using a Charged Coupled Device (CCD). Its finite pixel size integrates the optical information and limits the spatial resolution, whereas pixel-pitch provides the sampling interval. Spatial resolution can be improved if pixels of smaller sizes are used or equivalently if Geometric Super-Resolution technique is achieved. In this paper, we are reporting use of the Negative rect mask (NRM) at image plane to achieve Geometric Super-resolution through sub-pixeling. The NRM is scanned over CCD in sub-pixel steps and image data is gathered. The target is assumed to be static during the scanning process. The data collected through CCD with NRM coding and the position information of the scanning mask provides a mean to render the geometrically super resolved image. The work is demonstrated in one and two dimensions with computer simulation. The results are also applicable on CMOS based imaging. (C) 2018 Elsevier GmbH. All rights reserved.

关键词： Geometric superresolution Spatial resolution CCD-pixel Subpixel Mask scanning optical coding Computational decoding optical image processing

来源：评论

学校读者我要写书评

暂无评论

Cryptography based on the absorption/emission features of multicolor semiconductor nanocrystal quantum dots

引用

OPTICS EXPRESS 2004年第13期12卷 2925-2931页

作者： Zhou, M Chang, SD Grover, CP Natl Res Council Canada Inst Natl Measurement Stand Ottawa ON K1A 0R6 Canada

Further to the optical coding based on fluorescent semiconductor quantum dots (QDs), a concept of using mixtures of multiple single-color QDs for creating highly secret cryptograms based on their absorption/emission properties was demonstrated. The key to readout of the optical codes is a group of excitation lights with the predetermined wavelengths programmed in a secret manner. The cryptograms can be printed on the surfaces of different objects such as valuable documents for security purposes. (C) 2004 optical Society of America.

关键词： .codes semiconductor nanocrystals optical coding multiple single-color cryptograms

来源：评论

学校读者我要写书评

暂无评论

Precise Failure Location and Protection Mechanism in Long-Reach Passive optical Network

引用

JOURNAL OF LIGHTWAVE TECHNOLOGY 2016年第22期34卷 5175-5182页

作者： Zhang, Shicheng Ji, Wei Li, Xiao Huang, Kangrui Yin, Rui Shandong Univ Sch Informat Sci & Engn Jinan 250100 Shandong Peoples R China

In this paper, optical code domain reflectometer (OCDR) and optical time domain reflectometer (OTDR) are used for centralized monitoring and troubleshooting any fault occurring in the network. It combines the advantages of the OTDR scheme and the optical coding scheme, which can supervise the whole long-reach passive optical network in a cost-effective manner. Network management system in the central office can initialize monitoring, locating failure, and protection process by monitoring information. The scheme can locate the faulty point precisely by OTDR after determining the failed optical fiber link by the optical coding technique. The OTDR precise positioning and protection scheme can be carried out simultaneously, thus saving recovery time. Furthermore, network performance of OCDR and OTDR, recovery time, loss, cost, bit error rate of data signal transmission are also studied. The results obtained prove the feasibility and efficiency of the proposed network, and that it can support high network capacity.

关键词： Long-reach passive optical network (LR-PON) optical coding optical network survivability optical time domain reflectometer (OTDR)

来源：评论

学校读者我要写书评

暂无评论

Efficient and costless monitoring mechanism in metro-access network

引用

optical SWITCHING AND NETWORKING 2017年 25卷 117-123页

作者： Cheng, Zijing Li, Xiao Ji, Wei Space Star Aerosp Technol Applicat Co Ltd Beijing Peoples R China Shandong Univ Sch Informat Sci & Engn 27 Shanda South Rd Jinan 250100 Shandong Peoples R China

Fast and unambiguous link or node failure localization is very important and necessary in optical network. But it is not always clear what constitutes a good method to monitor the whole network. In an effort to understand the benefits and drawbacks of existing methods, we empirically present two state-of-the-art methods: monitoring trails method and optical coding method for their ability of monitoring time, cost, scalability and centralized management performance. Then a new fault location method combining the advantages of two schemes in the mesh-tree network that can be used for metro-access network is introduced. At the same time, performance analysis of monitoring scheme is obtained. It can be seen that the proposed method can monitor the whole optical network effectively with low cost and good scalability. The technique can support high network capacity.

关键词： Monitoring Mesh-tree network optical coding Monitoring trail allocation (MTA) Fiber Bragg Grating (FBG)

来源：评论

学校读者我要写书评

暂无评论

Extracting sub-exposure images from a single capture through Fourier-based optical modulation

引用

SIGNAL PROCESSING-IMAGE COMMUNICATION 2018年 60卷 107-115页

作者： Khan, Shah Rez Feldman, Martin Gunturk, Bahadir K. Istanbul Medipol Univ Dept Elect & Elect Engn Istanbul Turkey Louisiana State Univ Div Elect & Comp Engn Baton Rouge LA 70803 USA

Through pixel-wise optical coding of images during exposure time, it is possible to extract sub-exposure images from a single capture. Such a capability can be used for different purposes, including high-speed imaging, high-dynamic-range imaging and compressed sensing. In this paper, we demonstrate a sub-exposure image extraction method, where the exposure coding pattern is inspired from frequency division multiplexing idea of communication systems. The coding masks modulate sub-exposure images in such a way that they are placed in non-overlapping regions in Fourier domain. The sub-exposure image extraction process involves digital filtering of the captured signal with proper band-pass filters. The prototype imaging system incorporates a Liquid Crystal over Silicon (LCoS) based spatial light modulator synchronized with a camera for pixel-wise exposure coding. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Computational photography optical coding Pixel-wise exposure control

来源：评论

学校读者我要写书评

暂无评论

Signaling Free Localization of Link and Node Failures in an optical Mesh-Tree Network

引用

JOURNAL OF optical COMMUNICATIONS AND NETWORKING 2016年第4期8卷 263-271页

作者： Li, Xiao Ji, Wei Zhang, Shicheng Huang, Kangrui Shandong Univ Sch Informat Sci & Engn Jinan 250100 Shandong Peoples R China

A monitoring mechanism combining the advantages of a monitoring trails scheme and an optical coding scheme is proposed;the mechanism can be used in a metro-access network. optical encoders are centrally placed in an optical distribution network and at both sides of each remote node, which makes for much simpler installation and smaller management costs. A modified heuristic monitoring trail allocation algorithm is used for monitoring the inner links of the mesh network. The principle of the complete monitoring scheme and various fault scenes are displayed. The results show that the designed monitoring mechanism costs less and is easily scalable. This system can monitor not only the states of fiber links but also nodes in the network to alleviate the false alarm probability. It can also support high network capacity. Moreover, it can take a trade-off of the number of monitors and optical encoders.

关键词： Fiber Bragg gratings Monitoring trails (m-trails) Network survivability optical coding

来源：评论

学校读者我要写书评

暂无评论

The Theoretical Analysis and Design of coding BOTDR System With APD Detector

引用

IEEE SENSORS JOURNAL 2014年第8期14卷 2626-2632页

作者： Wan, Shengpeng Xiong, Yuhua He, Xingdao Nanchang Hangkong Univ Minist Educ Key Lab Nondestruct Test Nanchang 330063 Peoples R China

The signal-to-noise ratio and the coding gain of Brillouin optical time domain reflectometry system with APD detector are analyzed. In coding distributed optical fiber sensing system, there are a large number of multipath interferences (MPIs), which are proportional to the code length. The random shot noise caused by MPI will be generated before decoding and cannot be eliminated by decoding process. In addition, the shot noise power is proportional to the square of the code length;the thermal noise power increases linearly with the code length, then, the increase of the speed of the coding gain will be decreased with the increase of the code length. When the shot noise is much larger than the thermal noise, the coding gain will not be increased with the increase of the code length, but will maintain a constant value. This conclusion is in contradiction with the traditional conclusion. At the same time, the shot noise depends on the pulsewidth and power, but the thermal noise is independent on the pulsewidth and the power, so there exists an optimum code length for specific system.

关键词： Brillouin scattering distributed optical fiber sensor optical coding

来源：评论

学校读者我要写书评

暂无评论

Novel Brillouin optical Time-Domain Analyzer for Extreme Sensing Range Using High-Power Flat Frequency-Coded Pump Pulses

引用

JOURNAL OF LIGHTWAVE TECHNOLOGY 2015年第12期33卷 2623-2627页

作者： Le Floch, Sebastien Sauser, Florian Llera, Miguel Rochat, Etienne Haute Ecole ARC Metrol & Qual Engn Lab CH-2610 St Imier Switzerland Omnisens SA CH-1110 Morges Switzerland

In this paper, we propose a novel Brillouin optical time-domain analysis setup that combines simultaneous Brillouin gain/loss measurements with colour coding. This technique gives the advantage that the pump power can greatly be increased, compared to other coding schemes;thus, increasing the sensing range. A first measurement over a 200-km fiber loop is performed, with a 3-m spatial resolution and an accuracy of +/- 3 MHz (2s) at the end of the sensing fiber. In a second setup, high-power flat pump pulses are generated by applying an arbitrary waveform signal on a frequency shifter;thus, further increasing the performance of the novel Brillouin sensor. To the best of our knowledge, these are the best results obtained with a Brillouin sensor without Raman amplification.

关键词： Brillouin scattering distributed fiber sensors fiber optics sensors optical coding

来源：评论

学校读者我要写书评

暂无评论

PON Monitoring: Periodic Encoders With Low Capital and Operational Cost

引用

IEEE PHOTONICS TECHNOLOGY LETTERS 2008年第21-24期20卷 2039-2041页

作者： Fathallah, Habib Rad, Mohammad M. Rusch, Leslie A. Univ Laval Dept Elect & Comp Engn COPL Quebec City PQ G1V 0A6 Canada

We propose a novel and simple coding device for centralized monitoring of passive optical networks. Encoders have dual Bragg gratings forming a cavity producing periodic codes. These encoders reduce the cost of manufacturing, installation, inventory, and operation, while maintaining good performance and high capacity. We evaluate monitoring efficiency in terms of signal-to-noise ratio.

关键词： Monitoring network management optical code-division multiplexing (OCDM) optical coding passive optical network (PON) signal-to-noise ratio (SNR)

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：